Industrial automation controllers are special purpose computers used for the control of industrial machines and/or processes. While executing a stored program, they read inputs from one or more controlled machines/processes and, according to the logic of a contained control program, provide outputs to the same and/or different controlled machine(s)/process(es) based upon the inputs. Industrial controllers must provide “real-time” control (i.e., control in which control outputs are produced predictably and timely in response to given control inputs), and must provide for extremely reliable operation and recovery from faults. In this latter regard, critical data contained in processor registers and other volatile memory (e.g., DRAM, SRAM, SDRAM, etc.) of the controller must be saved or “backed-up” to a non-volatile memory (e.g., flash EEPROM, disk, etc.) in the event of loss of electrical power. Heretofore, this back-up operation has been performed under power supplied by a back-up power source integrated into the controller, typically a replaceable battery (e.g., a 3 volt lithium battery) or a capacitor permanently connected to the controller circuitry and permanently housed within the controller module.
FIG. 1 (prior art) shows an example of such an industrial automation controller 10 including a chassis 12 incorporating a number of modules 14, 16, 18, and 20 operably interconnected by means of a modular or fixed size backplane 22. In particular, a power supply module 14 receives electrical line power 24 as input (e.g., about 120 volts AC) and outputs operating power (e.g., about 5 volts DC) for distribution along the backplane 22 to the other modules 16, 18, and 20. A controller module 16 receives data along the backplane 22 from a network module 18 and at least one I/O module 20. The network module 18 provides an interface with a communication network 35 such as EtherNet, or ControlNet to receive system control data or data from other I/O modules and to allow data to be transmitted to/from other devices on the communication network 35. The I/O module 20 provides an interface for input and output signals along I/O lines 27 communicating with the controlled process or machine. Generally, during operation of the industrial controller 10, a program executed by the controller module 16 reads input data from the I/O module(s) and creates output data that are then sent along the backplane 22 to the network module 18 or to an I/O module 20. The controller module 16 includes at least one internal processor circuit board (main circuit board) 26 containing a battery or capacitor back-up electrical power source 28, volatile memory 30, and processor circuitry 32. The processor circuitry 32 comprises one or more suitable electronic controller or microprocessor devices such as an ASIC or a general purpose microprocessor that executes a stored control program, a programmable logic controller and/or the like. The battery may be a lithium battery as is generally known in the art. Such batteries are typically not rechargeable and hence must be replaced when their reserve power is below a minimum threshold. A capacitor back-up power source 28 can alternatively be used, but is not replaceable by the end-user and can lose energy capacity by exposure to long-term elevated temperatures. The volatile memory 30 can be, e.g., (synchronous) dynamic random access memory (S)DRAM that requires application of power to maintain its data integrity. Non-volatile memory 34 such as flash memory or disk is also provided. In the event of loss of operating power in the backplane 22 (e.g., due to interruption of the input line power 24 to the power supply module 14), the battery or other back-up power source 28 outputs a required back-up power to the controller module 16 to allow for completion of an “emergency save” operation in which the processor circuitry 32 saves its state (i.e., content of its registers and other volatile memory) and also saves data from the volatile memory 30 to the non-volatile memory 34 using the back-up power supplied by the back-up power source 28.
Whether the back-up power source 28 is a battery or a capacitor, these prior back-up power sources 28 have been integrated into the controller module 16 such that a switch from one type of back-up power source to another type by an end-user (e.g., from battery to capacitor) or replacement of the back-up power source is not possible. Such a switch might be required if the controller module 16 is to be moved from one environment (e.g. a factory) to another (e.g., a mine) where batteries are not allowed. Furthermore, battery replacement in these prior controllers requires that the housing of the controller module 16 be opened through an access door or the like to allow the old battery 28 to be disconnected from and the new battery connected to the controller module 16. This prior battery replacement operation is sometimes difficult or inconvenient or excessively time-consuming in an industrial environment, can be unsafe due to potential exposure to high-voltage electronics, and can require the controller module to be powered down during the replacement process. It is important to reduce the time required to replace a back-up power source to account for the possibility of a power failure occurring during the replacement operation and to allow for replacement of a controller back-up power source during controller operation. Also, if a back-up power source replacement operation is too difficult or inconvenient, it is possible that an end-user will not periodically replace the back-up power source as required.
In light of the foregoing, it has been deemed desirable to provide an energy storage module for an industrial automation controller, and an industrial automation controller module including such an energy storage module, wherein the energy storage module includes any desired suitable back-up energy source and wherein the energy storage module is specially adapted to ensure safe and reliable operation of itself and the industrial automation controller module to which it is mated.